1. Field of the Invention
This invention relates generally to a method and apparatus for recording an analog signal and, more particularly, to a method and apparatus for recording an analog signal as a pulse code modulated (PCM) signal incorporating error-correcting and parity information.
2. Description of the Prior Art
Recording and reproducing an analog signal, such as an audio signal, as a pulse-code-modulated (PCM) signal permits very high-grade recording and reproducing.
Both fixed- and rotating-head systems have been proposed for recording and reproducing PCM signals. Video tape recorders (VTR) have been used as a rotating head system for recording an audio PCM signal. In a VTR having two rotary heads, the heads are normally located diametrically opposed from each other, that is, 180.degree. apart, on a rotating tape-guide drum. A magnetic tape is wrapped about the tape-guide drum for substantially the same angular range. Each head traces or scans a track on the tape for each revolution of the drum. The audio signal to be recorded is converted into PCM data which has redundant data appended thereto to be used for error correction on reproduction. Such apparatus, for recording PCM data by means of a VTR, is disclosed in U.S. Pat. No. 4,138,694, and requires that the PCM data be converted to the format of a video signal before recording by the VTR.
In prior art apparatus using a VTR for recording PCM data, adding of parity data and error codes to the PCM signal has been accomplished by using buffer circuitry to delay the signal so that the additional information can be combined with the PCM data. However, such buffer circuits cause signal processing to become quite complex. The apparatus used to reproduce the signal can also become very complicated.